JP2020500873A - Conditioning method of ethylene epoxidation catalyst and related method of formation of ethylene oxide - Google Patents

Abstract

A method for conditioning an ethylene epoxidation catalyst is provided. The conditioning method comprises contacting an ethylene epoxidation catalyst comprising a support having silver and rhenium promoter deposited thereon with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C and up to 250 ° C for at least 2 hours. Contacting the ethylene epoxidation catalyst with the conditioning feed gas is performed in the absence of ethylene in the epoxidation reactor. A related method for epoxidation of ethylene is also provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Application No. 62 / 429,111, filed December 2, 2016, which is incorporated herein by reference.

  Ethylene oxide is a valuable raw material known for use as a versatile chemical intermediate in the manufacture of a wide variety of chemicals and products. For example, ethylene oxide is used to produce ethylene glycol, which is used in many diverse applications, including antifreeze in automotive engines, hydraulic brake fluids, resins, fibers, solvents, paints, plastics, films, household and industrial It can be found in a variety of products, including cleaners, pharmaceuticals, and personal care products such as cosmetics, shampoos, and the like.

  Ethylene oxide is formed by reacting ethylene with oxygen in the presence of a silver-based ethylene epoxidation catalyst. The selectivity of an ethylene epoxidation catalyst, also known as “efficiency,” determines the ability of the epoxidation catalyst to convert ethylene to the desired reaction product, ethylene oxide, with respect to competing by-products (eg, CO 2 and H 2 O). And typically expressed as a percentage of moles of ethylene oxide formed per mole of ethylene reacted.

Modern silver-based ethylene epoxidation catalysts are very selective for the formation of ethylene oxide, and have a theoretical maximum selectivity of 6/7 or 85.7 mol%, based on the stoichiometry of the reaction equation. Higher selectivity values can be achieved.
7 C2H4 + 6 O2 → 6 C2H4O + 2 CO2 + 2 H2O
See Kirk-Othmer, Encyclopedia of Industrial Chemistry, 4th Edition, Volume 9, 1994, pp. 926. Such "high selectivity" catalysts typically include silver, rhenium cocatalyst, and optionally, alkali metals (e.g., cesium, lithium, etc.), alkaline earth metals (e.g., magnesium), transition metals (e.g., magnesium). And one or more additional cocatalysts, such as, for example, tungsten), and main group non-metals (eg, sulfur), which are described, for example, in US Pat. Nos. 4,761,394 and 4,766. No. 105.

  In many cases, the selectivity determines the economic attractiveness of the ethylene epoxidation process. For example, on a commercial scale, even a small, eg, 1%, increase in selectivity of the epoxidation process can substantially reduce the annual operating cost of a large ethylene oxide plant. Therefore, much work has been done to find process conditions that improve catalyst selectivity and allow for full utilization of catalyst performance.

  The high selectivity catalyst can be adjusted prior to the start of the epoxidation reaction to remove residual organic compounds or ammonia from the catalyst preparation, or to improve catalyst performance (eg, activity and / or selectivity). The conditioning process may be performed before the onset of ethylene oxide production and may generally involve contacting the catalyst with a non-reactive feed gas. The duration and conditions of the catalyst bed during the conditioning period, such as feed gas composition and temperature, can significantly affect the catalyst performance observed after reaching stable operation. Accordingly, a need has arisen for a conditioning method that provides improved catalyst performance.

U.S. Pat. No. 4,761,394 U.S. Pat. No. 4,766,105

  A method for conditioning an ethylene epoxidation catalyst is provided. The conditioning method comprises contacting an ethylene epoxidation catalyst comprising a support having silver and rhenium promoter deposited thereon with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C and up to 250 ° C for at least 2 hours. Contacting the ethylene epoxidation catalyst with the conditioning feed gas is performed in the absence of ethylene in the epoxidation reactor.

  Also provided is a method for epoxidation of ethylene, the method comprising the steps of contacting an ethylene epoxidation catalyst comprising a carrier with silver and rhenium co-catalyst deposited thereon with a conditioning feed gas comprising oxygen for a period of at least 2 hours above 180 ° C and up to 250 ° C. C., wherein the contacting of the ethylene epoxidation catalyst with the conditioning feed gas is carried out in the absence of ethylene in the epoxidation reactor. Contacting the ethylene epoxidation catalyst within with an epoxidation feed gas comprising ethylene, oxygen, and an organic chloride.

  Also provided is a method of improving the selectivity of an ethylene epoxidation catalyst in an ethylene epoxidation process, wherein the conditioning method comprises the steps of: Contacting the gas with the gas at a temperature above 180 ° C. and up to 250 ° C. for a period of at least 2 hours, wherein the contact of the ethylene epoxidation catalyst with the conditioning feed gas is carried out in the absence of ethylene in the epoxidation reactor. And contacting the ethylene epoxidation catalyst in the epoxidation reactor with an epoxidation feed gas comprising ethylene, oxygen, and organic chloride.

  Some specific exemplary embodiments of the present disclosure may be understood by referring, in part, to the following description and the accompanying drawings.

It is a bar graph of experiment 1-14, 85.7% of average selectivity about Comparative Examples 1-5, 86.9% of average selectivity about Examples 6 and 7, and 88.4% of average selectivity about Examples 8-14. %. The effect of temperature during conditioning for 24 hours at an oxygen concentration of 5% is shown. The effect of oxygen concentration for 24 hours at two temperatures of 185 ° C and 245 ° C is shown. 3 shows the effect of conditioning time at a temperature of 245 ° C. 21 is a graph showing the oxygen conversion (%) observed for the first 12 hours after introduction of the epoxidation feed gas, observed in Comparative Example 18 and Example 19 below. 20 is a graph showing the selectivity (%) of the first 12 hours after introduction of the epoxidation feed gas, observed in Comparative Example 18 and Example 19 below.

  While the present disclosure is susceptible to various modifications and alternative forms, certain exemplary embodiments are shown in the drawings and are described herein in more detail. However, while the description of certain exemplary embodiments is not intended to limit the invention to the particular forms disclosed, on the contrary, this disclosure is partially illustrated by the appended claims. It should be understood that they are intended to cover all modifications and equivalents as provided.

  The present disclosure provides a method for conditioning an ethylene epoxidation catalyst and related methods for epoxidation of ethylene. As described in detail below, an ethylene epoxidation catalyst comprising a support having silver and rhenium promoters deposited thereon is conditioned with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C. and up to 250 ° C. for a period of at least 2 hours. Contacting, wherein the contacting of the ethylene epoxidation catalyst with the conditioning feed gas is performed in the absence of ethylene, and it has been found that contacting results in an unexpected improvement in catalyst performance. .

  In particular, the conditioning method of the present disclosure provides that the ethylene epoxidation catalyst comprising the silver and rhenium co-catalyst-deposited carrier has the same ethylene epoxidation using or without conventional catalyst conditioning methods. It achieves a higher maximum catalyst selectivity than does the catalyst. Similarly, the conditioning method of the present disclosure also provides that the ethylene epoxidation catalyst comprising the silver and rhenium co-catalyst-deposited carrier has the same ethylene epoxidation using or not using conventional catalyst conditioning methods. Overall higher average catalyst selectivities and / or higher ethylene oxide production can be achieved than with epoxidation catalysts.

  Further, the ethylene epoxidation catalyst conditioned in accordance with the conditioning method of the present disclosure also advantageously provides a lower oxygen conversion level than the same ethylene epoxidation catalyst exhibits when the starting feed gas comprising ethylene and oxygen is introduced. Can be shown. This is particularly advantageous as it allows for a process that is more stable and easily controllable, and thereby safer. Lower oxygen conversion levels may result in faster leakage of oxygen to the reactor outlet, which may allow for a faster increase in oxygen concentration in the reactor gas loop. This allows the oxygen concentration and / or oxygen feed rate in the starting feed gas to be increased at a faster rate, which is the same or substantially the same as the epoxidized feed gas utilized during normal ethylene oxide production. The amount of time required before the same concentration of oxygen is achieved can be significantly reduced. Further, the methods disclosed herein can have other advantages, such as significantly shortening the duration of the startup process and / or improving the overall profitability of the epoxidation process.

  The conditioning and ethylene epoxidation methods described herein can be performed in a number of ways, but in a gas phase process, i.e., contacting the feed with an ethylene epoxidation catalyst present as a solid material in the gas phase The process is preferably carried out typically in a packed bed of a multitubular epoxidation reactor. Generally, the ethylene epoxidation process is performed as a continuous process. Epoxidation reactors typically include a heat exchanger for heating or cooling the catalyst. The methods provided herein can be applied to fresh catalysts and aging catalysts that are restarted after prolonged and / or unexpected periods of shutdown.

  Further, the methods provided herein include a precursor of an ethylene epoxidation catalyst (ie, comprising silver in an unreduced (cationic) form, comprising, after reduction, a support on which silver and a rhenium promoter are deposited. The carrier may further include components necessary for obtaining an ethylene epoxidation catalyst. In this case, the reduction may be achieved by contacting the precursor with a conditioning feed gas comprising oxygen.

  Generally, an ethylene epoxidation catalyst comprising a support on which silver and rhenium promoters have been deposited is heated in an epoxidation reactor to a temperature above 180 ° C. and up to 250 ° C. using an external heat source such as a coolant heater. For example, the coolant can be heated using an external heat source (eg, a coolant heater) and supplied to a coolant circuit of the epoxidation reactor. The heated coolant supplied to the reactor coolant circuit transfers heat to the ethylene epoxidation catalyst in the reactor, thereby increasing the temperature to above 180 ° C and up to 250 ° C.

  It should be noted that the temperature values used herein refer to the gas phase temperature in the catalyst bed as measured directly through the use of one or more thermocouples. As known to those skilled in the art, one or more axially disposed thermocouples can be placed in the selected reaction tube as a means of monitoring the temperature in the multitubular epoxidation reactor. Typically, the epoxidation reactor contains a total of about 1,000 to about 12,000 reaction tubes, of which 5 to 50, and preferably 5 to 30, reaction tubes contain thermocouples. The thermocouple typically extends the entire length of the reaction tube and is usually centered on the tube by one or more positioning devices. Preferably, each thermocouple has from 5 to 10 measurement points along its length (e.g., a multipoint thermocouple), allowing an operator to observe the catalyst bed temperature profile. To enable a meaningful representative measurement, determining which particular reaction tubes in the reactor should contain thermocouples and where they should be located is a skill of the artisan. Is within the range. For accuracy, it is preferred that a plurality of equally spaced thermocouples be utilized, in which case, as is known to those skilled in the art, the temperature of a catalyst bed having a relatively uniform load density will be a multiple gas temperature Calculated by taking the numerical average of the measurements.

  Optionally, contacting the ethylene epoxidation catalyst with the sweep gas at any suitable temperature prior to contacting the ethylene epoxidation catalyst with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C and up to 250 ° C for a period of at least 2 hours. The sweep gas may be an inert gas, typically such as nitrogen, argon, methane, or the like, or a combination thereof. To convert a significant portion of the organic nitrogen compounds that may be used in the production of ethylene epoxidation catalysts into nitrogen-containing gases, which are swept into the gas stream and removed from the catalyst, It may be particularly advantageous to contact the ethylene epoxidation catalyst with a sweep gas at a temperature above 150 ° C. In addition, any water can be removed from the catalyst. The initiation of the spent ethylene epoxidation catalyst may or may not require the use of a sweep gas, but may be used frequently. Further details regarding these procedures can be found in US Pat. No. 4,874,879, which is incorporated herein by reference.

  According to the method of the present disclosure, after the epoxidation catalyst has reached a temperature of greater than 180 ° C. and up to 250 ° C., it is contacted with a conditioning feed gas comprising oxygen for at least 2 hours. As mentioned above, the ethylene epoxidation catalyst is contacted with the conditioning feed gas in the absence of ethylene, thereby preventing the reaction between ethylene and oxygen from taking place during this period. It should be noted that the temperature at which the conditioning feed gas is initially introduced into the ethylene epoxidation catalyst is not limited, and thus, in some embodiments, the conditioning feed gas is initially introduced at a temperature less than 180 ° C. And may optionally be introduced before, after or simultaneously with the sweep gas (if used).

  Typically, the ethylene epoxidation catalyst is above 180 ° C and up to 250 ° C, or at least 185 ° C to 250 ° C, or at least 190 ° C to 250 ° C, or at least 195 ° C to 250 ° C, or at least 200 ° C. Up to 250C, or more than 180C up to 245C, or at least 185C up to 245C, or at least 190C up to 245C, or at least 195C up to 245C, or at least 200C up to 245C, Or greater than 180 ° C up to 240 ° C, or at least 185 ° C up to 240 ° C, or at least 190 ° C up to 240 ° C, or at least 195 ° C up to 240 ° C, or at least 200 ° C up to 240 ° C, or at least 220 ° C. Up to 250 ° C, or at least 20C up to 245C, or at least 220C up to 240C, or more than 180C up to 220C, or at least 185C up to 220C, or at least 190C up to 220C, or at least 195C up to 220C. At or at a temperature of at least 200 ° C to a maximum of 220 ° C.

  Further, the ethylene epoxidation catalyst may be treated at one or more temperatures within the above temperature range for at least 2 hours, typically 2 to 200 hours, or 2 to 100 hours, or 2 to 72 hours, or 2 to 48 hours. Hours, or 2 to 36 hours, or 2 to 24 hours, or 6 to 200 hours, or 6 to 72 hours, or 6 to 48 hours, or 6 to 36 hours, or 6 to 24 hours, or 12 to 72 hours, Or 12 to 48 hours, or 12 to 36 hours, or 12 to 24 hours, or 24 to 48 hours. The ethylene epoxidation catalyst may be contacted with the conditioning feed gas for more than 200 hours, but generally does not provide additional benefits and is economically attractive because the catalyst does not produce ethylene oxide during this time It is not believed.

  In embodiments where the ethylene epoxidation catalyst is contacted with the conditioning feed gas at a temperature that is in the lower portion of the given temperature range, it is desirable to perform the conditioning method for a time in the upper portion of the given time range. There are cases. For example, if the ethylene epoxidation catalyst is contacted with the conditioning feed gas at a temperature greater than 180 ° C. to a maximum of 220 ° C., or at least 185 ° C. to a maximum of 220 ° C., the time for contacting the ethylene epoxidation catalyst with the conditioning feed gas may be from 6 to 72 hours, or 6-48 hours, or 6-24 hours, or 12-72 hours, or 12-48 hours, or 12-36 hours, or 12-24 hours, or 24-72 hours, or 24-48 hours It may be. Similarly, if the ethylene epoxidation catalyst is contacted with the conditioning feed gas at a temperature that is in the upper portion of the given temperature range, the conditioning method may be performed over a period of time in the lower portion of the given time range. It may be desirable. For example, if the ethylene epoxidation catalyst is contacted with the conditioning feed gas at a temperature of at least 220 ° C. to a maximum of 250 ° C., or at least 220 ° C. to a maximum of 245 ° C., the time for contacting the ethylene epoxidation catalyst with the conditioning feed gas may be from 2 to 2. 72 hours, or 2 to 48 hours, or 2 to 36 hours, or 2 to 24 hours, or 2 to 12 hours, or 6 to 72 hours, or 6 to 48 hours, or 6 to 36 hours, or 6 to 24 hours Or 6 to 12 hours.

  During at least two hours of contacting the ethylene epoxidation catalyst with the conditioning feed gas in the absence of ethylene, the temperature may be maintained at a single temperature or multiple temperatures in a temperature range of greater than 180 ° C and up to 250 ° C. The coolant temperature and / or flow rate can be adjusted as needed to maintain a temperature of greater than 180 ° C and up to 250 ° C throughout this period. Optionally, during all or part of the period of contacting the ethylene epoxidation catalyst with the conditioning feed gas, the temperature is ramped up using a ramp function, a series of steps, or non-linearly up to a maximum temperature of 250 ° C. For example, the temperature can be gradually increased toward a temperature suitable for epoxidation. As known to those skilled in the art, the temperature can be manipulated manually or automatically using a coolant (heating) circuit temperature controller.

  The conditioning feed gas used in the present disclosure includes oxygen and an inert gas such as nitrogen, methane, argon, helium, or a combination thereof. Suitably, the conditioning feed gas does not contain ethylene. Optionally, the conditioning feed gas may further include an organic chloride, steam, carbon dioxide, or a combination thereof.

  Oxygen may be provided in any suitable form, such as in its substantially pure molecular form or in a mixture such as air. Typically, the oxygen concentration in the conditioning feed gas is at least 0.1 mol%, or at least 0.5 mol%, or at least 1 mol%, or at least 1 mol%, on the same basis, relative to the total conditioning feed gas. 2 mol%, or at least 3 mol%, or at least 4 mol%, or at least 5 mol%. Similarly, the oxygen concentration in the conditioning feed gas is typically up to 30 mol%, or up to 21 mol%, or up to 15 mol%, or up to 12 mol%, on the same basis, for all conditioning feed gases. Mol%, or up to 10 mol%. In some embodiments, oxygen is present in the conditioning feed gas at 0.1 mol% to 30 mol%, or 0.1 mol% to 21 mol%, on the same basis, based on the total conditioning feed gas. Or 0.1 mol% to 15 mol%, or 0.1 mol% to 10 mol%, or 0.1 mol% to 5 mol%, or 0.5 mol% to 21 mol%, or 0.5 mol% １５15 mol%, or 0.5 mol% to 10 mol%, or 0.5 mol% to 5 mol%, or 1 mol% to 30 mol%, or 1 mol% to 21 mol%, or 1 mol% It may be present at a concentration of 15 mol%, or 1 mol% to 10 mol%, or 1 mol% to 5 mol%, or 5 mol% to 21 mol%, or 5 mol% to 15 mol%.

  The inert gas is generally at least 70 mol%, or at least 75 mol%, or at least 80 mol%, or at least 85 mol%, or at least 85 mol%, on the same basis, based on the total conditioning feed gas, in the conditioning feed gas. It is present at a concentration of at least 90 mol%, or at least 95 mol%. Similarly, the inert gas is typically present in the conditioning feed gas at up to 99.9 mol%, or at most 99.5 mol%, or at most 99 mol%, on the same basis, relative to the total conditioning feed gas. It is present at a concentration of up to 98 mol%, or up to 98 mol%, or up to 95 mol%. Furthermore, the inert gas is present in the conditioning feed gas in a concentration of 70 mol% to 99.9 mol%, a concentration of 70 mol% to 99.5 mol%, on the same basis, relative to the total conditioning feed gas; It may be present at a concentration of 70 mol% to 95 mol%, or 80 mol% to 98 mol%, or 80 mol% to 95 mol%.

  Optionally, the conditioning feed gas may further include an organic chloride. Examples of suitable organic chlorides for use in the present disclosure include chlorinated hydrocarbons having 1 to 8 carbon atoms. Examples of these include, but are not necessarily limited to, methyl chloride, ethyl chloride, ethylene dichloride, vinyl chloride, and combinations thereof. When used, organic chlorides are typically present in the conditioning feed gas at 0.1 parts per million or more per part by volume (ppmv), on the same basis, relative to the total conditioning feed gas, or It is present at a concentration of at least 0.3 ppmv, or at least 0.5 ppmv, or at least 1 ppmv, or at least 2 ppmv. Similarly, when used, organic chlorides will typically be present in the conditioning feed gas at up to 25 ppmv, or at most 22 ppmv, or at most 20 ppmv, or at most, on the same basis, based on the same conditioning feed gas. Present at a concentration of 15 ppmv, or up to 10 ppmv, or up to 5 ppmv. Optionally, the organic chloride is present in the conditioning feed gas in the same standard, based on the same conditioning feed gas, as 0.1 to 25 ppmv, 0.1 to 20 ppmv, 0.1 to 10 ppmv, 0.1 to 5 ppmv. May be present.

  The order and manner in which the components of the conditioning feed gas are combined before contacting the ethylene epoxidation catalyst are not limited, and they may be combined simultaneously or sequentially. However, as will be appreciated by those skilled in the art, it may be desirable for safety reasons to add oxygen to the conditioning feed gas at the same time as or after the addition of the inert gas. Similarly, the concentration of various components (eg, oxygen, inert gas, organic chlorides, etc.) present in the conditioning feed gas may be maintained at a single concentration throughout the conditioning process or may be at a given concentration as described above. It can be adjusted within the range.

  During at least two hours of contacting the ethylene epoxidation catalyst with the conditioning feed gas in the absence of ethylene, the reactor inlet pressure is typically up to 4000 kPa (absolute), or up to 3500 kPa (absolute), or up to 3000 kPa (absolute pressure) or a maximum of 2500 kPa (absolute pressure). The reactor inlet pressure is typically at least 500 kPa (absolute). The gas flow through the epoxidation reactor is expressed in gas hourly space velocity (“GHSV”), which is the volumetric flow rate of the feed gas at standard temperature and pressure (ie, 0 ° C., 1 atmosphere) at the catalyst bed volume. (Ie, the volume of the epoxidation reactor containing the ethylene epoxidation catalyst). GHSV describes how many times per hour the feed gas replaces the volume of the epoxidation reactor when the gas is at standard temperature and pressure (ie, 0 ° C., 1 atmosphere). When the process disclosed herein is performed in a gas phase process involving a packed catalyst bed, the GHSV during conditioning is preferably in the range of 200-10000 Nl / (1 hour). However, the conditioning method disclosed herein is not limited to any particular GHSV, and optionally, when there is no gas flow in the epoxidation reactor, ie, when the epoxidation reactor is pressurized with the conditioning feed gas. It can be implemented when done.

  After conditioning the epoxidation catalyst according to the methods described herein, the epoxidation process is typically initiated by contacting the ethylene epoxidation catalyst with a starting feed gas comprising ethylene and oxygen. Optionally, the starting feed gas may further include an organic chloride, carbon dioxide, water vapor, an inert gas, or any combination thereof.

  Typically, the ethylene concentration in the starting feed gas is at least 5 mol%, or at least 10 mol%, or at least 15 mol%, or at least 20 mol%, on the same basis, based on the total starting feed gas. is there. Similarly, the ethylene concentration in the starting feed gas is typically up to 50 mol%, or up to 45 mol%, or up to 30 mol%, or up to 25 mol%, on the same basis, based on the total starting feed gas. Mol%, or up to 20 mol%. In some embodiments, ethylene is present in the starting feed gas at 5 mol% to 50 mol%, or 5 mol% to 45 mol%, or 5 mol%, on the same basis, relative to the total starting feed gas. -30 mol%, or 5 mol% -25 mol%, or 10 mol% -50 mol%, or 10 mol% -45 mol%, or 10 mol% -30 mol%, or 10 mol% -25 mol% It may be present in a concentration.

  The oxygen concentration in the starting feed gas is typically at least 0.5 mol%, or at least 1 mol%, or at least 2 mol%, or at least 2. mol%, on the same basis, based on the total starting feed gas. 5 mol%, or at least 5 mol%. Similarly, the oxygen concentration in the starting feed gas is typically up to 15 mol%, or up to 12 mol%, or up to 10 mol%, or up to 5 mol%, on the same basis, based on the total starting feed gas. Mol%. In some embodiments, oxygen is present in the starting feed gas in the same basis, based on the same basis, from 0.1 mol% to 15 mol%, or from 1 mol% to 12 mol%, or 1 mol%. It may be present at a concentration of from 10 mol% to 10 mol%, or 2 mol% to 10 mol%. It may be advantageous for the starting feed gas to have a lower oxygen concentration than the epoxidized feed gas utilized during normal ethylene oxide production, as lower oxygen concentrations in the starting feed gas result in lower oxygen conversion levels. Hot spots in the catalyst bed are more avoided and the process will be more easily controllable. However, as noted above, ethylene epoxidation catalysts conditioned in accordance with the conditioning method of the present disclosure, when the initial feed gas is first introduced, advantageously have lower oxygen conversion levels than the same epoxidation catalyst indicates. Can be shown. Therefore, it is also possible to increase the oxygen concentration in the starting feed gas and / or the oxygen supply rate at a faster rate, since an oxygen concentration equivalent to that utilized during normal ethylene oxide production is achieved. The amount of time required before the start can be significantly reduced.

  Optionally, the starting feed gas may further include an organic chloride. Examples of suitable organic chlorides for use in the present disclosure include chlorinated hydrocarbons having 1 to 8 carbon atoms. Examples of these include, but are not necessarily limited to, methyl chloride, ethyl chloride, ethylene dichloride, vinyl chloride, and combinations thereof. When used, organic chlorides are typically present in the starting feed gas at 0.1 ppmv or more, or 0.3 ppmv or more, or 0.5 ppmv or more, on the same basis, relative to the total starting feed gas. Present at a concentration of Similarly, when used, the organic chloride concentration in the starting feed gas is typically up to 25 ppmv, or up to 22 ppmv, or up to 20 ppmv, on the same basis, for all starting feed gases. Optionally, the organic chloride concentration in the starting feed gas may be 0.1-25 ppmv, or 0.3-20 ppmv, on the same basis, for all starting feed gases. Typically, as the feed gas composition changes and / or one or more of the operating conditions change, the concentration of organic chloride in the starting feed gas is also adjusted to maintain the optimum concentration. can do. For further disclosure regarding the optimization of organic chlorides, see, for example, U.S. Patent Nos. 7,193,094 and 7,485,597, which are incorporated herein by reference.

  Optionally, the starting feed gas may be substantially free, and preferably completely free, of the nitrogen-containing reaction modifier. That is, the starting feed gas may include less than 100 ppm of the nitrogen-containing reaction modifier, preferably less than 10 ppm, more preferably less than 1 ppm, and most preferably 0 ppm. As used herein, the term "nitrogen-containing reaction modifier" refers to a gaseous compound or volatile liquid that can exist or form as a nitrogen oxide under oxidizing conditions. Examples of nitrogen-containing reaction modifiers include NO, NO2, N2O3, N2O4, N2O5, or any substance capable of forming one of the foregoing gases under epoxidation conditions (e.g., hydrazine, hydroxylamine, ammonia , Organic nitro compounds (such as nitromethane, nitroethane, nitrobenzene), amines, amides, organic nitrites (such as methyl nitrite), nitriles (such as acetonitrile), and combinations thereof, but are not limited thereto.

  Optionally, the starting feed gas may further include carbon dioxide. If used, carbon dioxide will typically be present in the starting feed gas up to 6 mole%, or up to 4 mole%, or up to 3 mole%, on the same basis, based on the total starting feed gas. Or it is present at a concentration of up to 2 mol%, or up to 1 mol%. Similarly, when used, the carbon dioxide concentration in the starting feed gas is typically at least 0.1 mol%, or at least 0.2 mol%, on the same basis, based on the total starting feed gas. Or at least 0.3 mol%, or at least 0.5 mol%, or at least 1 mol%. In some embodiments, the carbon dioxide is present in the starting feed gas at 0.1 mol% to 6 mol%, or 0.1 mol% to 4 mol%, on the same basis, based on the total starting feed gas. Or 0.1 mol% to 3 mol%, or 0.1 mol% to 2 mol%. Suitably, carbon dioxide may be present in the starting feed gas at the same or substantially the same concentration as the epoxidized feed gas utilized during normal ethylene oxide production.

  Typically, the ethylene epoxidation catalyst is first contacted with a starting feed gas comprising ethylene and oxygen at a temperature above 180 ° C and up to 250 ° C. After a while, heat is generated by the epoxidation reaction of ethylene, and the temperature further rises. During the time of contacting the ethylene epoxidation catalyst with the starting feed gas, the temperature may be greater than 180C to a maximum of 320C, or at least 185C to a maximum of 300C, or at least 185C to a maximum of 280C, or at least 220C to a maximum. It may be maintained at a single temperature or multiple temperatures ranging from 300 ° C, or at least 220 ° C to a maximum of 280 ° C, or at least 230 ° C to a maximum of 280 ° C. As those skilled in the chemical engineering arts know, there are many suitable methods for regulating the temperature in a chemical process, including, but not limited to, temperature, flow rate, and coolant pressure, supply These include gas composition, space velocity, and reactor inlet pressure, any of which may be utilized as needed to regulate and / or maintain the temperature of the process.

  During the time of contacting the ethylene epoxidation catalyst with the starting feed gas, the reactor inlet pressure is typically up to 4000 kPa (absolute), or up to 3500 kPa (absolute), or up to 3000 kPa (absolute), or The maximum is 2500 kPa (absolute pressure). The reactor inlet pressure is typically at least 500 kPa (absolute). Preferably, when the process disclosed herein is performed in a gas phase process involving a packed catalyst bed, the starting GHSV is in the range of 500-10000 Nl / (1 hour).

  The order and manner in which the components of the starting feed gas are combined before contacting the ethylene epoxidation catalyst are not limited, and they may be combined simultaneously or sequentially. The order and manner in which the components of the starting feed gas are combined may be selected for convenience and / or safety reasons. Further, as will be appreciated by those skilled in the art, the concentration of various components present in the starting feed gas (eg, ethylene, oxygen, inert gas, organic chlorides, etc.) is maintained at a single concentration throughout the start. Or it can be adjusted within the above given concentration ranges. For example, throughout all or part of the time the ethylene epoxidation catalyst is in contact with the starting feed gas, the concentration of various components (eg, ethylene, oxygen, inert gas, organic chlorides, etc.) present in the starting feed gas may be Can be progressively increased (or decreased) towards a concentration that is the same or substantially the same as the epoxidation feed gas utilized during normal ethylene oxide production.

  Optionally, after conditioning the ethylene epoxidation catalyst according to the methods described herein, the epoxidation catalyst may be subjected to a heat treatment at any time after introduction of the starting feed gas. For example, the epoxidation catalyst may be raised to a temperature above 250 ° C., typically up to 320 ° C., and contacted with a feed gas comprising oxygen and ethylene. Further details regarding suitable heat treatments can be found, for example, in U.S. Patent Nos. 7,102,022 and 7,485,597, which are incorporated herein by reference.

  A further description of the epoxidation catalyst used in the present disclosure is provided herein. Epoxidation catalysts suitable for use in the methods described herein, commonly referred to as high selectivity catalysts, include a support on which silver and rhenium promoters have been deposited. The carrier (also known as "support") can be selected from a wide range of materials. Such carrier materials can be natural or artificial inorganic materials, including silicon carbide, clay, pumice, zeolites, charcoal, and alkaline earth metal carbonates such as calcium carbonate. Preferred are refractory support materials such as alumina, magnesia, zirconia, silica, and mixtures thereof. The most preferred support material is α-alumina. In some embodiments, the support comprises at least 80%, 90%, or 95% by weight, based on the weight of the catalyst, of α-alumina, eg, up to 99.9%, especially up to 99% by weight. Α-alumina in an amount of

  Carriers suitable for use herein may be selected from those having a wide variety of physical properties, including, but not limited to, shape, size, surface area, water absorption, crush strength, abrasion resistance, overall Includes pore volume, median pore size, pore size distribution, and the like.

  Suitable shapes for the carrier include any of a wide variety of shapes known for carriers, including pills, blocks, tablets, pieces, pellets, rings, spheres, wagon wheels, trapezoids, Donut, amphora, ring, Raschig ring, honeycomb, monolith, saddle, cylinder, hollow cylinder, multilobe cylinder, cross-split hollow cylinder (eg, a cylinder with at least one split extending between walls), side-to-side gas These include, but are not limited to, cylinders with channels, cylinders with two or more gas channels, and ribbed or finned structures. Cylinders are often circular, but other cross-sections such as ellipses, hexagons, quadrilaterals, triangles, and multilobes may be useful. For further description of a multilobe carrier, reference may be made to US Patent No. 8,871,677, which is incorporated herein by reference.

  Further, the size of the support is generally not limited and may include any size suitable for use in an epoxidation reactor. For example, the carrier can be cylindrical with a length of 5 to 15 millimeters ("mm"), an outer diameter of 5 to 15 mm, and an inner diameter of 0.2 to 4 mm. In some embodiments, the carrier may have a length to outside diameter ratio of 0.8 to 1.2. Furthermore, the carrier can be in the form of a hollow cylinder having a wall thickness of 1 to 7 mm. Taking advantage of the present disclosure, the preferred shape and size of the carrier (eg, the length and inner diameter of the tube in the epoxidation reactor, taking into account, for example, the type and configuration of the epoxidation reactor in which the carrier is used) Choosing) is within the ability of those skilled in the art.

  In general, the surface area of the support indicates the amount of surface area per gram of support available for deposition of the catalytic material (eg, silver). The surface area of a carrier suitable for use herein is not strictly critical; for example, 0.1 to 10 m2 / g, or 0.5 to 5 m2 / g, on the same basis, relative to the weight of the carrier. g, or 0.7-3 m2 / g, or at least 0.1 m2 / g, or at least 0.3 m2 / g, or at least 0.5 m2 / g, or at least 0.6 m2 / g, or at most 10 m2 / g, or It may be up to 5 m2 / g, or up to 3 m2 / g. As used herein, "surface area" is defined by Brunauer, S .; , Emmet, P .; Y. and Teller, E.A. , J. et al. Am. Chem. Soc. , 60, 309-16 (1938). E. FIG. T. (Brunauer, Emmett and Teller) is understood to refer to the surface area of the carrier as measured according to the method.

  The water absorption of a carrier is typically expressed as the weight of water that can be absorbed into the pores of the carrier, relative to the weight of the carrier, and is therefore reported as grams of water per gram of carrier, and the unit is `` g / g ". Typically, the water absorption of a carrier suitable for use herein is, for example, from 0.2 to 1.2 g / g, or at least 0.2 g / g, on the same basis, based on the weight of the carrier. g, or at least 0.25 g / g, or at least 0.3 g / g, or at most 0.8 g / g, or at most 0.75 g / g, or at most 0.7 g / g. As used herein, the term “water absorption” is understood to refer to the water absorption of the carrier as measured according to the following procedure: First, a representative sample of about 100 g of the carrier is taken at 110 ° C. Dry for a minimum of 1 hour. The samples are then cooled in a desiccator and the dry weight (D) of each sample is determined to the nearest 0.01 g. The sample is then placed in a pot of distilled water and boiled for 30 minutes. While the water is boiling, cover the sample with water and use a setter pin or similar device to separate the sample from the bottom and sides of the pan and from each other. After boiling for 30 minutes, the samples were transferred to room temperature water and soaked for another 15 minutes. After returning to room temperature, each sample was then gently wiped with a damp, lint-free linen or cotton cloth to remove any excess moisture from the surface and to reduce the saturated weight (M) of each sample to 0.1. The determination is made in units of 01 g. The wiping operation can be accomplished by gently rolling the test specimen onto a damp cloth saturated with water, and then pressing the test piece sufficiently to remove any water that drips from the cloth. Excessive wiping should be avoided as it will introduce errors from withdrawing water from the pores of the sample. The sample must be weighed immediately after wiping. The entire operation must be completed as quickly as possible to minimize errors due to evaporation of moisture from the sample. The water absorption (A) is expressed as the weight of water absorbed relative to the weight of the dry carrier and is determined using the following formula: A = [(MD) / D], where water absorption The rate is expressed in units of grams of water per gram of carrier ("g / g")). If the density of water is corrected under the measured conditions, the water absorption can also be expressed in units of "cc / g". Alternatively, if the water absorption is measured according to the procedure described above, it may be convenient to express the water absorption in units of grams of water absorbed per 100 grams of carrier (eg, 60 g / 100 g), It can also be expressed as the weight percent of water absorbed per 100 g of carrier (eg, 60%). The water absorption of the support can be positively correlated with "porosity" and is therefore used interchangeably with the term "porosity", which in the field of catalyst supports is usually the porosity of the open cells of the support. It is understood to mean. In general, as the water absorption of the support increases, the ease of depositing the catalyst material on the support increases. However, at higher water absorption, the support, or epoxidation catalyst comprising the support, may have lower crush strength or abrasion resistance.

  The crush strength of a carrier is typically expressed as the amount of compressive force required to crush the carrier, relative to the length of the carrier, and is therefore reported as the amount of force per millimeter of the carrier, in units of: It may be abbreviated as “N / mm”. The crush strength of a carrier suitable for use herein is not strictly critical, but should have sufficient crush strength to allow its use in commercial production of ethylene oxide. Typically, the crush strength of a carrier suitable for use herein is, for example, at least 1.8 N / mm, or at least 2 N / mm, or at least 3.5 N / mm, or at least 5 N / mm, and In many cases, it can be 40 N / mm, or 25 N / mm, or 15 N / mm. As used herein, the term "crush strength" is understood to refer to the crush strength of the carrier as measured according to ASTM D6175-03, wherein the test sample is left as it is after its preparation, i.e. the steps of the method. Except for 7.2 (this represents the step of drying the test sample). In this crushing strength test method, the crushing strength of a carrier is typically measured as the crushing strength of hollow cylindrical particles having an outer diameter of 8.8 mm, an inner diameter of 3.5 mm, and a length of 8 mm.

  In general, the abrasion resistance of a carrier indicates the tendency of the carrier to generate fines during transport, handling, and use. The abrasion resistance of a carrier suitable for use herein is not strictly critical, but should be sufficiently robust to allow its use in commercial production of ethylene oxide. Typically, carriers suitable for use herein may exhibit up to 50%, or up to 40%, or up to 30% friction, typically at least 5%, or at least 10%, Or at least 15%, or at least 20%. As used herein, “abrasion resistance” is understood to refer to the abrasion resistance of the carrier as measured according to ASTM D4058-92, and the test sample is left as it is after its preparation, ie, step 6 of the method. .4, which represents the step of drying the test sample. In this test method, the abrasion resistance of the carrier is typically measured as the abrasion resistance of hollow cylindrical particles having an outer diameter of 8.8 mm, an inner diameter of 3.5 mm, and a length of 8 mm.

  The total pore volume, median pore size, and pore size distribution of the carrier can be measured by a conventional mercury intrusion porosimetry device in which liquid mercury is forced into the pores of the carrier. Higher pressures are required to force mercury into smaller pores, and the measured pressure increment corresponds to the volume increment of the pierced pore, and thus to the size of the pore in the incremental volume. As used herein, pore size distribution, median pore size, and pore volume are based on the Micromeritics Autopore 9200 model (130o contact angle, mercury with a surface tension of 0.480 N / m, and mercury compression corrections applied. ) As measured by mercury intrusion porosimetry up to a pressure of 2.1 × 10 8 Pa. As used herein, central pore size is understood to mean the pore size corresponding to the point in the pore size distribution where 50% of the total pore volume is smaller (or larger) than this point. You.

  The total pore volume of a carrier suitable for use herein is not strictly critical, for example, at least 0.20 mL / g, at least 0.30 mL / g, at least 0.40 mL / g, at least 0.4 mL / g. It can be 50 mL / g, typically up to 0.80 mL / g, up to 0.75 mL / g, or up to 0.70 mL / g. Generally, as the total pore volume of the support increases, the ability to deposit catalytic material on the support increases. However, at higher total pore volumes, the support, or epoxidation catalyst comprising the support, may have lower crush strength or abrasion resistance. The median pore size of a carrier suitable for use herein is not strictly critical and can be, for example, 0.50-50 μm. Further, carriers suitable for use herein may have a monomodal, bimodal, or multimodal pore size distribution.

  In addition to the support, ethylene epoxidation catalysts suitable for use in the present disclosure include those having silver and rhenium promoters deposited thereon. Optionally, the ethylene epoxidation catalyst can be an alkali metal promoter (eg, lithium, sodium, potassium, rubidium, cesium, and combinations thereof), a co-promoter (eg, sulfur, phosphorus, boron, tungsten, Molybdenum, chromium, and combinations thereof), additional metal promoters (eg, alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, etc.), titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, Gallium, germanium, and combinations thereof), and / or combinations thereof.

  Broadly speaking, silver is deposited on the carrier in an amount sufficient to catalyze the gas phase reaction of ethylene and oxygen to produce ethylene oxide. When preparing ethylene epoxidation catalysts containing different amounts of silver on a support of similar packing density, it is convenient to compare the epoxidation catalysts on a silver weight basis, which is typically As a function of the total weight of the silver. As used herein, unless otherwise specified, the total weight of the epoxidation catalyst is the total weight of the epoxidation catalyst deposited thereon, including the support, and silver, rhenium co-catalyst, and any co-catalyst (s). It is understood to refer to the weight of all components. Typically, epoxidation catalysts suitable for use herein comprise from 1% to 55%, or from 1% to 50% by weight, on the same basis, based on the total weight of the epoxidation catalyst. Or 5% to 40% by weight, or 8% to 35% by weight, or 10% to 30% by weight, or at least 10% by weight, or at least 15% by weight, or at most 45% by weight, or at most 40% by weight Contains silver in% amounts. The upper and lower limits of the suitable amount of silver can be varied appropriately depending on the particular catalyst performance characteristics or desired effects, or other variables involved, including economic factors.

  Alternatively, the amount of silver contained in the ethylene epoxidation catalyst can be expressed in terms of the mass of silver per unit volume of epoxidation catalyst loaded in the epoxidation reactor (eg, in the catalyst bed). In this way, a comparison of silver loading between epoxidation catalysts prepared on supports of different packing densities can be made. Finally, since the catalyst bed contains a defined amount of epoxidation catalyst, this method of comparing the amount of silver deposited on the epoxidation catalyst is appropriate. Accordingly, epoxidation catalysts suitable for use herein are at least 50 kg / m3, or at least 100 kg / m3, or at least 100 kg / m3, on the same basis, based on the total volume of epoxidation catalyst loaded in the catalyst bed. Silver may be included in an amount of 125 kg / m3, or at least 150 kg / m3. Similarly, epoxidation catalysts suitable for use herein may have, on the same basis, up to 500 kg / m3, or up to 450 kg / m3, or up to the total volume of epoxidation catalyst loaded in the catalyst bed. Silver may be included in an amount up to 400 kg / m3, or up to 350 kg / m3. Preferably, the epoxidation catalyst has an amount of 50 to 500 kg / m3, or 100 to 450 kg / m3, or 125 to 350 kg / m3, on the same basis, based on the total volume of the epoxidation catalyst loaded in the catalyst bed. And may contain silver.

  Epoxidation catalysts suitable for use herein, calculated as the amount of rhenium relative to the total weight of the epoxidation catalyst, can provide, on the same basis, a rhenium co-catalyst deposited on a support of 0.01-50 m Mol / kg, or 0.1-50 mmol / kg, or 0.1-25 mmol / kg, or 0.1-20 mmol / kg, or 0.5-10 mmol / kg, or 1-6 mmol / kg. kg, or at least 0.01 mmol / kg, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol In an amount of mol / kg, or up to 50 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 6 mol / kg. Good. Stated another way, the amount of rhenium cocatalyst, expressed relative to the surface area of the support, is preferably between 0.25 and 10 μmol / m 2, or between 0.5 and 5 μmol / m 2, or between 1 and 3 μmol. / M2 in the epoxidation catalyst. For convenience, the amount of rhenium promoter deposited on the epoxidation catalyst is measured as metal, regardless of the form in which it is present.

  Optionally, epoxidation catalysts suitable for use herein are alkali metal cocatalysts deposited on a support on the same basis, calculated as the amount of elements based on the total weight of the epoxidation catalyst (e.g., Lithium, sodium, potassium, rubidium, cesium, or a combination thereof) from 0.01 to 500 mmol / kg, or from 0.01 to 400 mmol / kg, or from 0.1 to 300 mmol / kg, or from 0.1 to 300 mmol / kg. ２５０250 mmol / kg, or 0.5-200 mmol / kg, or 1-100 mmol / kg, or at least 0.01 mmol / kg, or at least 0.05, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or less Also 1.5 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or up to 500 mmol / kg, or up to 400 mmol / kg, or up to 300 mmol / kg, or up to 250 mmol / kg, Alternatively, it may further comprise up to 200 mmol / kg, or up to 150 mmol / kg, or up to 100 mmol / kg. For convenience, the amount of alkali metal deposited on the epoxidation catalyst is measured as an element, regardless of the form in which it is present.

  It should be understood that the amount of alkali metal cocatalyst deposited on the support need not be the total amount of alkali metal present in the epoxidation catalyst. Rather, the amount of deposition reflects the amount of alkali metal promoter that has been added to the support (eg, by impregnation). As such, the amount of alkali metal cocatalyst deposited on the support can be fixed in the support, for example, by calcination, or cannot be extracted in a suitable solvent such as water, or a lower alkanol, or an amine, or a combination thereof. , And alkali metals that do not have a promoting effect. It should further be understood that the source of the alkali metal promoter may be the carrier itself. That is, the support can contain an extractable amount of an alkali metal cocatalyst that can be extracted with a suitable solvent such as water or a lower alkanol, thus depositing or redepositing the alkali metal cocatalyst on the support. A solution that can be prepared.

  In embodiments where the ethylene epoxidation catalyst comprises an alkali metal promoter, it may be beneficial for the catalyst to comprise a combination of two or more alkali metal promoters. Non-limiting examples include cesium and rubidium combinations, cesium and potassium combinations, cesium and sodium combinations, cesium and lithium combinations, cesium, rubidium and sodium combinations, cesium, potassium, and Combinations of sodium, combinations of cesium, lithium, and sodium, combinations of cesium, rubidium, and sodium, combinations of cesium, rubidium, potassium, and lithium, and combinations of cesium, potassium, and lithium.

  Optionally, epoxidation catalysts suitable for use herein are, based on the same criteria, co-catalysts (e.g., sulfur, Phosphorus, boron, tungsten, molybdenum, chromium, or a combination thereof) from 0.01 to 500 mmol / kg, or from 0.01 to 100 mmol / kg, or from 0.1 to 50 mmol / kg, or from 0.1 to 50 mmol / kg. ２０20 mmol / kg, or 0.5-10 mmol / kg, or 1-6 mmol / kg, or at least 0.01 mmol / kg, or at least 0.05, or at least 0.1 mmol / kg, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / k Or at least 2 mmol / kg, or at least 3 mmol / kg, or at most 100 mmol / kg, or at most 50 mmol / kg, or at most 40 mmol / kg, or at most 30 mmol / kg, or at most 20 mmol / kg, Or it may further comprise up to 10 mmol / kg, or up to 5 mmol / kg. For convenience, the amount of co-catalyst deposited on the epoxidation catalyst is measured as an element, regardless of the form in which it is present.

  In embodiments where the ethylene epoxidation catalyst comprises a co-promoter, the co-promoter comprises a first co-promoter selected from sulfur, phosphorus, boron, and combinations thereof, and tungsten, molybdenum, chromium, and combinations thereof. It may be particularly advantageous if it comprises a combination of a second co-promoter selected from the group. The amount of the first co-promoter deposited on the support is calculated as the amount of elements (eg, sulfur, phosphorus, and / or boron) relative to the total weight of the epoxidation catalyst, and is, on the same basis, 0.2% ５０50 mmol / kg, or 0.5-45 mmol / kg, or 0.5-30 mmol / kg, or 1-20 mmol / kg, or 1.5-10 mmol / kg, or 2-6 mmol / kg kg, or at least 0.2 mmol / kg, or at least 0.3, or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg. Or at least 1.75 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or at most 50 mmol / kg, or In amounts of up to 45 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 6 mmol / kg. possible. The amount of the second co-promoter deposited on the support is calculated as the amount of the element (eg, tungsten, molybdenum, and / or chromium) relative to the total weight of the epoxidation catalyst and is, on the same basis, 0.1% -40 mmol / kg, or 0.15-30 mmol / kg, or 0.2-25 mmol / kg, or 0.25-20 mmol / kg, or 0.3-10 mmol / kg, or 0.4 mmol Mol / kg to 5 mmol / kg, or at least 0.1 mmol / kg, or at least 0.15, or at least 0.2 mmol / kg, or at least 0.25 mmol / kg, or at least 0.3 mmol / kg. Or at least 0.35 mmol / kg, or at least 0.4 mmol / kg, or at least 0.45 mmol / kg, or at least 0.5 mmol / kg, or up to 40 mmol / kg, or up to 35 mmol / kg, or up to 30 mmol / kg, or up to 25 mmol / kg, or up to 20 mmol / kg, or up to 15 mmol / kg, or up to It can be in an amount of 10 mmol / kg, or up to 5 mmol / kg. Additionally, the first and second co-promoters have a molar ratio of the first co-promoter to the second co-promoter of greater than 1, or at least 1.25, at least 1.5, at least 2, or at least 2.5. Depositing can be beneficial. More preferably, the molar ratio of the first co-promoter to the second co-promoter is at most 20, at most 15, at most 10, or at most 7.5. Further, it is preferred that the molar ratio of the rhenium promoter to the second co-promoter can be greater than 1, at least 1.25, or at least 1.5. More preferably, the molar ratio of the rhenium promoter to the second co-promoter can be up to 20, up to 15, or up to 10.

  Optionally, epoxidation catalysts suitable for use herein are further metal cocatalysts deposited on the support on the same basis, calculated as the amount of elements based on the total weight of the epoxidation catalyst (e.g., Beryllium, magnesium, calcium, strontium, alkaline earth metals such as barium, titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium, germanium, manganese, etc.) in an amount of 0.01 to 500 mmol / kg, Or 0.01-100 mmol / kg, or 0.1-50 mmol / kg, or 0.1-20 mmol / kg, or 0.5-10 mmol / kg, or 1-6 mmol / kg, or at least 0.01 mmol / kg, or at least 0.05, or at least 0.1 mmol / kg, Or at least 0.5 mmol / kg, or at least 1 mmol / kg, or at least 1.25 mmol / kg, or at least 1.5 mmol / kg, or at least 2 mmol / kg, or at least 3 mmol / kg, or In an amount of up to 100 mmol / kg, or up to 50 mmol / kg, or up to 40 mmol / kg, or up to 30 mmol / kg, or up to 20 mmol / kg, or up to 10 mmol / kg, or up to 5 mmol / kg. It may additionally be included. For convenience, the amount of additional metal promoter in the epoxidation catalyst is measured as an element, regardless of the form in which it is present.

  The degree of benefit obtained within the concentration limits defined above for the rhenium co-catalyst and / or any co-catalyst (s), alone or with the rhenium co-catalyst and / or any co-catalyst (s) Epoxidation conditions, catalyst preparation conditions, physical and chemical properties of the carrier used, amount of silver deposited on the epoxidation catalyst, deposition on the epoxidation catalyst Such as the amount of rhenium cocatalyst deposited, the amount of any cocatalyst (s) deposited on the epoxidation catalyst (if any), and the amount of other cations and anions present in the epoxidation catalyst. It can vary depending on one or more properties and properties. Therefore, the limits defined above were chosen to cover the widest possible variation in properties and properties.

  Well-known methods can be used to analyze the amount of silver, rhenium promoter, and optional promoter (s) deposited on the support. One skilled in the art can, for example, employ a mass balance to determine the amount of any of these deposited components. As an example, when weighing the support before and after deposition of the silver and rhenium promoter, the difference between the two weights is equal to the amount of silver and rhenium promoter deposited on the support, from which the amount of rhenium promoter deposited Can be calculated. In addition, the amount of silver and cocatalyst deposited can be calculated based on the concentration of silver and cocatalyst in the impregnation solution (s) and the ratio of the total weight in the finished epoxidation catalyst. Alternatively, the amount of co-catalyst deposited on the support may also be determined by known leaching methods, wherein the amount of metal leachate present in the support and the amount of metal leachate present in the epoxidation catalyst are: Determined independently, the difference between the two measurements reflects the total amount of cocatalyst deposited on the support.

  The preparation of silver-containing ethylene epoxidation catalysts is known in the art. The specific method of preparing an ethylene epoxidation catalyst suitable for use herein is not limited, and thus, any method known in the art can be used. For a description of the preparation of an ethylene epoxidation catalyst, see U.S. Pat. Nos. 6,368,998 and 6,656,874, which are incorporated herein by reference.

  Generally speaking, the ethylene epoxidation process of the present disclosure can be performed in various ways known in the art, and it is preferred that the epoxidation process be performed as a continuous gas phase process. The ethylene epoxidation process can be performed by any known epoxidation reactor (eg, ethylene and ethylene and (Any reaction vessel used to react oxygen). Further, multiple epoxidation reactors can be used in parallel.

  One commercial example of a suitable epoxidation reactor is a vertical shell-and-tube heat exchanger, where a shell is used to regulate the temperature of the epoxidation reactor with a coolant (eg, a heat transfer fluid such as tetralin). , Water, etc.) and the plurality of tubes are substantially parallel elongated tubes containing an ethylene epoxidation catalyst. The size and number of tubes can vary from reactor to reactor, but typical tubes used in commercial reactors can have a length of 3-25 meters, 5-20 meters, or 6-15 meters . Similarly, the reaction tubes can have a tube inner diameter of 5-80 millimeters, 10-75 millimeters, or 20-60 millimeters. The number of tubes present in the epoxidation reactor can vary widely and can be in the thousands range, for example, up to 22,000, or 1,000-11,000, or 1,500-18,500. possible.

  The portion of the epoxidation reactor that contains the ethylene epoxidation catalyst (eg, the reaction tube) is commonly referred to as a "catalyst bed." Generally, the amount of ethylene epoxidation catalyst in the catalyst bed, the height of the catalyst bed, and the packing density of the epoxidation catalyst in the catalyst bed (ie, "tube packing density") are, for example, present in the epoxidation reactor. It can vary widely depending on the size and number of tubes and the size and shape of the epoxidation catalyst. However, a typical range of tube packing density can be 400-1500 kg / m3. Similarly, a typical range for the height of the catalyst bed can be 50% to 100% of the length of the reaction tube. In embodiments where the height of the catalyst bed is less than 100% of the length of the reaction tube, the remainder of the tube may be empty or, optionally, contain particles of non-catalytic or inert material.

  According to the method of the present disclosure, an ethylene epoxidation catalyst comprising a carrier with silver and rhenium promoters deposited thereon is treated with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C. and up to 250 ° C. for at least 2 hours. After contacting in the absence of ethylene in the oxidation reactor, the ethylene epoxidation catalyst is contacted with an epoxidation feed gas comprising ethylene, oxygen, and organic chloride. Optionally, the epoxidation feed gas may further include carbon dioxide, water vapor, nitrogen, an inert gas such as methane, ethane, argon, helium, and the like, and combinations thereof.

  Ethylene may be present in the epoxidation feed gas at widely varying concentrations. However, ethylene is typically present in the epoxidized feed gas at least 5 mol%, or at least 8 mol%, or at least 10 mol%, or at least 10 mol%, on the same basis, relative to the total epoxidized feed gas. It is present at a concentration of 12 mol%, or at least 14 mol%, or at least 20 mol%, or at least 25 mol%. Similarly, ethylene is typically present in the epoxidation feed gas at up to 65 mol%, or at most 60 mol%, or at most 55 mol%, or at most 50 mol%, or at most 48 mol%, on the same basis. %. In some embodiments, ethylene is present in the epoxidation feed gas in the same basis, based on the same epoxidation feed gas, as 5 mol% to 60 mol%, or 10 mol% to 50 mol%, or 12 mol%. It may be present at a concentration of from about mol% to about 48 mol%.

  Generally, the oxygen concentration in the epoxidation feed gas should be lower than the oxygen concentration that would form a combustible mixture at either the reactor inlet or the reactor outlet under typical operating conditions. In many cases, in practice, the oxygen concentration in the epoxidation feed gas will depend on the predetermined percentage of oxygen that will form a combustible mixture at either the reactor inlet or the reactor outlet under typical operating conditions ( For example, 95%, 90%, etc.). Although the oxygen concentration can vary over a wide range, the oxygen concentration in the epoxidized feed gas is typically at least 0.5 mol%, or at least 1 mol%, on the same basis, based on the total epoxidized feed gas. Mol%, or at least 2 mol%, or at least 3 mol%, or at least 4 mol%, or at least 5 mol%. Similarly, the oxygen concentration in the epoxidation feed gas is typically up to 20 mol%, or up to 15 mol%, or up to 12 mol%, or up to 12 mol%, on the same basis, based on the total epoxidation feed gas. The maximum is 10 mol%. In some embodiments, the oxygen is present in the epoxidized feed gas at 1 mol% to 15 mol%, or 2 mol% to 12 mol%, or 3 mol%, on the same basis, based on the total epoxidized feed gas. It may be present at a concentration of from 10 mol% to 10 mol%. Typically, the required temperature decreases as the oxygen concentration in the epoxidation feed gas increases. However, as noted above, in practice, flammability is generally a limiting factor in the maximum oxygen concentration in the epoxidized feed gas. Thus, to stay outside the flammable range, the oxygen concentration of the epoxidized feed gas may decrease as the ethylene concentration of the epoxidized feed gas increases. Taking into account the overall epoxidation feed gas composition, as well as other operating conditions such as, for example, pressure and temperature, determining the suitable concentration of oxygen to be included in the epoxidation feed gas is within the ability of those skilled in the art. Within range.

  Typically, the concentration of organic chlorides in the epoxidized feed gas is at least 0.1 parts per million by volume (ppmv) or less, on the same basis, for all epoxidized feed gases. It is present at a concentration of 3 ppmv or more, or 0.5 ppmv or more. Similarly, the organic chloride concentration in the epoxidized feed gas is typically up to 25 ppmv, or up to 22 ppmv, or up to 20 ppmv, on the same basis, for all epoxidized feed gases. Further, the organic chloride concentration in the epoxidized feed gas may be 0.1-25 ppmv, or 0.3-20 ppmv, on the same basis, for all epoxidized feed gases. Typically, as the epoxidation feed gas composition changes and / or one or more of the operating conditions change, the concentration of the organic chloride in the epoxidation feed gas also maintains an optimal concentration. Can be adjusted as follows. For further disclosure regarding the optimization of organic chlorides, see, for example, U.S. Patent Nos. 7,193,094 and 7,485,597, which are incorporated herein by reference.

  Optionally, the epoxidation feed gas may be substantially free, and preferably completely free of nitrogen-containing reaction modifier. That is, the epoxidation feed gas may contain less than 100 ppm of the nitrogen-containing reaction modifier, preferably less than 10 ppm, more preferably less than 1 ppm, and most preferably 0 ppm.

  Optionally, the epoxidation feed gas may further include carbon dioxide. When present, carbon dioxide is typically present in the epoxidation feed gas at 0.10 mol% or more, or 0.12 mol% or more, on the same basis, based on the total epoxidation feed gas, or It is present at a concentration of at least 0.15 mol%, or at least 0.17 mol%, or at least 0.20 mol%, or at least 0.22 mol%, or at least 0.25 mol%. Similarly, carbon dioxide is generally present in the epoxidized feed gas at up to 10 mol%, or at most 8 mol%, or at most 5 mol%, or at most 3 mol%, based on the same epoxidation feed gas, on the same basis. It is present in a concentration of up to 2.5 mol%, or up to 2.5 mol%. In some embodiments, carbon dioxide is present in the epoxidized feed gas in the same basis, from 0.10 mol% to 10 mol%, or from 0.15 mol% to 5 mol%, relative to the total epoxidation feed gas. It may be present in a concentration of from about 0.2% to about 0.2% to about 3%, or from about 0.25% to about 2.5%. Carbon dioxide is produced as a reaction by-product and is typically introduced into the epoxidation feed gas as an impurity (eg, by using a recycle gas stream in the epoxidation process). Carbon dioxide generally adversely affects catalyst performance, with increasing temperatures as the concentration of carbon dioxide present in the epoxidation feed gas increases. Thus, in commercial production of ethylene oxide, at least a portion of the carbon dioxide is removed from the recycle gas stream (eg, via a carbon dioxide separation system) to maintain an acceptable level of carbon dioxide in the epoxidation feed gas. It is common to remove continuously.

  Optionally, the epoxidation feed gas may further include water vapor. Generally, steam is produced as a combustion byproduct in the epoxidation reactor and is typically introduced into the epoxidation reactor as an impurity in the epoxidation feed gas by use of a recycle gas stream. When present, water vapor is typically present in the epoxidation feed gas at up to 5 mol%, or at most 3 mol%, or at most 2 mol%, on the same basis, relative to the total epoxidation feed gas. Or it is present at a concentration of up to 1 mol%, or up to 0.5 mol%. Alternatively, the concentration of water vapor can be expressed as the partial pressure of water vapor present in the epoxidation feed gas, which is the volume fraction of water vapor present in the epoxidation feed gas at the reactor inlet by the reactor inlet pressure. It can be calculated by multiplying by a percentage (eg, mole fraction). Thus, when present, the steam is supplied at a partial pressure of steam in the inlet feed of up to 1000 kPa, or up to 50 kPa, or up to 40 kPa, or up to 35 kPa, or up to 30 kPa, up to 25 kPa, up to 20 kPa, or up to 15 kPa The inlet feed may be present in the wastewater at a concentration such that

  The epoxidation feed gas may optionally further include an inert gas such as nitrogen, methane, or a combination thereof. If used, an inert gas can be added to the epoxidation feed gas to increase the oxygen flammable concentration. If desired, the inert gas may be present in the epoxidized feed gas in at least 5 mol%, or at least 10 mol%, or at least 20 mol%, or at least 20 mol%, based on the same epoxidized feed gas. It may be present at a concentration of 25 mol%, or at least 30 mol%. Similarly, the inert gas may be present in the epoxidized feed gas in a maximum of 80 mol%, or a maximum of 75 mol%, or a maximum of 70 mol%, or a maximum of 65 mol%, based on the same amount of epoxidation feed gas. % May be present. In some embodiments, the inert gas comprises from 20 mol% to 80 mol%, or from 30 mol% to 70 mol%, on the same basis, based on the total epoxidation feed gas, in the epoxidation feed gas. It may be present in a concentration.

  Ethylene epoxidation processes can vary significantly between different ethylene oxide plants, depending at least in part on initial plant design, subsequent expansion projects, availability of feedstock, type of epoxidation catalyst used, process economics, etc. It can be carried out under a wide range of operating conditions which can vary. Examples of such operating conditions include temperature, reactor inlet pressure, gas flow through the epoxidation reactor (commonly expressed as gas hourly space velocity or "GHSV"), and ethylene oxide production rate (generally, (Described in terms of speed).

  To achieve a reasonable commercial ethylene oxide production rate, the ethylene epoxidation reaction is typically conducted at a temperature of 180 ° C or higher, or 190 ° C or higher, or 200 ° C or higher, or 210 ° C or higher, or 225 ° C or higher. Will be implemented. Similarly, the temperature is typically 325C or lower, or 310C or lower, or 300C or lower, or 280C or lower, or 260C or lower. Further, the temperature may be between 180C and 325C, or between 190C and 300C, or between 210C and 300C.

  The ethylene epoxidation process disclosed herein is typically performed at a reactor inlet pressure of 500-4000 kPa, or 1200-2500 kPa (absolute). Various well-known devices can be used to measure reactor inlet pressure, for example, pressure indicating transducers, gauges, and the like. For example, it is within the capabilities of those skilled in the art to select a suitable reactor inlet pressure in view of the particular type of epoxidation reactor, desired productivity, and the like.

  As mentioned above, the gas flow through the epoxidation reactor is expressed in GHSV. In general, as GHSV increases, catalyst selectivity increases for any given operating speed. However, for a fixed catalyst amount, an increase in GHSV generally leads to an increase in energy costs, and therefore there is usually an economic trade-off between higher catalyst selectivity and increased operating costs. Typically, in a gas phase epoxidation process, the GHSV is between 1,500 and 10,000 per hour.

  The rate of production of ethylene oxide in the epoxidation reactor is typically described in terms of operating speed, which refers to the amount of ethylene oxide produced per hour per unit volume of catalyst. As known to those skilled in the art, operating speeds include temperature, reactor inlet pressure, GHSV, and epoxidation feed gas composition (eg, ethylene concentration, oxygen concentration, carbon dioxide concentration, organic chloride concentration, etc.). Without limitation, a function of several different variables. In general, for a given set of conditions, increasing the temperature under those conditions will increase the working speed and consequently the ethylene oxide production. However, this increase in temperature can often reduce catalyst selectivity and accelerate catalyst aging. Typically, the working speed in most plants is 50-400 kg of ethylene oxide per kg of catalyst per hour (kg / m3 / h), or 120-350 kg / m3 / h.

  Those of skill in the art having the benefit of this disclosure will appreciate, for example, temperature, reactor inlet pressure, GHSV, and operating speed, depending on plant design, equipment constraints, epoxidation feed gas composition, age of ethylene epoxidation catalyst, etc. Will be able to select the appropriate operating conditions.

  Ethylene oxide produced by the ethylene epoxidation process disclosed herein can be recovered using methods known in the art. In some embodiments, if desired, ethylene oxide is further reacted with water, alcohol, carbon dioxide, or amine according to known methods to form ethylene glycol, ethylene glycol ether, ethylene carbonate, or ethanolamine, respectively. can do.

  Conversion to 1,2-ethanediol or 1,2-ethanediol ether can include, for example, reacting ethylene oxide with water, suitably using an acidic or basic catalyst. For example, ethylene oxide is converted to an acid catalyst (e.g., 0.5-1.0% by weight sulfuric acid) in a liquid phase reaction to produce mainly 1,2-ethanediol and less 1,2-ethanediol ether. ), At a temperature of 50 ° C to 70 ° C and a pressure of 1 bar (absolute), or 130 ° C to 240 ° C and 20 to 40 bar (absolute) in the gas phase reaction, based on the total reaction mixture At a pressure of), preferably in the absence of a catalyst, with a 10-fold molar excess of water. Generally, as the proportion of water decreases, the proportion of 1,2-ethanediol ether in the reaction mixture increases. The 1,2-ethanediol ether thus produced can be a diether, triether, tetraether, or subsequent ether. Alternative 1,2-ethanediol ethers can be prepared by converting ethylene oxide with an alcohol, particularly a primary alcohol such as methanol or ethanol, thereby replacing at least a portion of the water with the alcohol.

  Conversion to ethanolamine can include, for example, reacting ethylene oxide with ammonia. Anhydrous or aqueous ammonia can be used, but anhydrous ammonia is typically used to promote the production of monoethanolamine. For methods applicable to the conversion of ethylene oxide to ethanolamine, see, for example, US Pat. No. 4,845,296, which is incorporated herein by reference.

  Ethylene glycol and ethylene glycol ethers can be used in a wide variety of industrial applications, for example, in the fields of foods, beverages, tobacco, cosmetics, thermoplastic polymers, curable resin systems, detergents, heat transfer systems, and the like. Ethylene carbonate can be used, for example, as a precursor in the production of ethylene glycol or as a diluent, especially as a solvent. Ethanolamine can be used, for example, in the processing of natural gas ("sweetening").

  Having generally described the present invention, a further understanding may be obtained by reference to the following examples, which are provided for illustrative purposes only and are intended to be limiting unless otherwise specified. do not do.

Examples 1 to 14
Examples 1 to 5 for comparison, Examples 6 to 14 according to the present invention
Microreactor Catalyst Test In the following examples, an ethylene epoxidation catalyst as described in U.S. Pat. No. 4,766,105 was used that included silver and rhenium promoters deposited on an alpha-alumina support. .

  4.41 grams of the ground catalyst sample (14-20 mesh) were loaded into a stainless steel U-shaped microreactor tube. The end of each tube was connected to a gas flow system that allowed gas flow through the catalyst bed in "single flow" operation. The catalyst-containing portion of each tube was immersed in a molten metal bath (heat medium) used to control the temperature.

  For each catalyst sample, a conditioning feed gas having a composition as shown in Table 1 was applied at a gas flow of 1760 GHSV for a period of 6 to 72 hours at a temperature between 160 ° C. and 245 ° C. as shown in Table 1. To the catalyst bed. The inlet gas pressure was 1880 kPa (absolute pressure).

Following the period shown in Table 1 ("conditioning period"), the temperature was adjusted to 235 ° C and the feed gas composition was adjusted to the epoxidized feed gas as follows:
In Comparative Examples 1 and 3, the conditioning gas using only nitrogen resulted in a very active catalyst, so that the feed gas to each catalyst bed was such that after the conditioning period, catalyst runaway or very high oxygen conversion was observed. An epoxidation feed gas containing 10% by volume (% v) ethylene, 7% by volume oxygen, 3% by volume carbon dioxide, 3 ppmv of ethyl chloride, and a nitrogen balance to prevent overruns Was adjusted to The reactor flow rate was adjusted to 3850 GHSV for each catalyst bed. After 24 hours, the epoxidation feed gas fed to each catalyst bed was subjected to 30% by volume of ethylene, 8.4% by volume of oxygen, 1.26% by volume of carbon dioxide, 1.5 ppmv of ethyl chloride, and a nitrogen balance. It was adjusted. The temperature was then adjusted so that the ethylene oxide concentration was 3.61% by volume in each of the outlet gas streams corresponding to a working speed of 273 kg / m3 / h. In addition, for each catalyst bed, the concentration of ethyl chloride in the epoxidation feed gas was adjusted between 1 and 5 ppmv to obtain maximum selectivity at a constant ethylene oxide concentration of 3.61% by volume in each of the outlet gas streams.

  In Comparative Examples 2, 4-5 and Examples 6-14, after the conditioning period, the feed gas to each catalyst bed was 30 vol% ethylene, 8.4 vol% oxygen, 1.26 vol% dioxide. Adjusted to epoxidation feed gas containing carbon, 3 ppmv ethyl chloride, and nitrogen balance. For each catalyst bed, the reactor flow was adjusted to 3850 GHSV and the temperature was kept constant for about 24 hours to allow the catalyst to equilibrate, after which each of the outlet gas streams corresponding to a working speed of 273 kg / m3 / h Was adjusted so that the ethylene oxide concentration became 3.61% by volume. In addition, for each catalyst bed, the ethyl chloride concentration in the epoxidation feed gas was adjusted between 1-5 ppmv to obtain maximum selectivity at a constant ethylene oxide concentration of 3.61% by volume in each of the outlet gas streams.

  While maintaining a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream and adjusting the ethyl chloride concentration to achieve maximum selectivity, a cumulative ethylene oxide production of 0.15 kT / m3 ("kT / m3 CumEO ").

  For catalyst testing and comparison purposes, the catalyst age is calculated by dividing the total ethylene oxide production (e.g., using metric kilotons "kT") on a mass basis by the catalyst loading reactor capacity (e.g., cubic meters "m3"). It can be conveniently expressed in terms of the division. Thus, Table 1 provides the performance of each of Comparative Examples 1-5 and Examples 6-14 with respect to the maximum selectivity achieved with CumEO between 0.07 and 0.15 kT / m3, which indicates that About 11 to 22 days. Further, FIG. 1A is a bar graph of Experiments 1-14, with an average selectivity of 85.7% for Comparative Examples 1-5, 86.9% for Examples 6 and 7 (at low temperature), and The average selectivity for Examples 8 to 14 is 88.4%.

As will be appreciated by those skilled in the art, the "activity" of an ethylene epoxidation catalyst generally refers to the rate of reaction of ethylene to ethylene oxide per unit of ethylene epoxidation catalyst volume in an epoxidation reactor, typically , Expressed as the temperature required to maintain a given ethylene oxide production rate. Thus, with respect to Table 1 below, the activity is expressed as the temperature required to maintain a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream, which corresponds to a working rate of 273 kg / m3 / h Is equivalent to

  Examples 6 to 14 (according to the invention) compare the ethylene epoxidation catalyst with a conditioning feed gas containing oxygen, at a temperature above 180 ° C and in the absence of ethylene, as compared to examples 1 to 5 (comparative). After contacting, the ethylene epoxidation catalyst shows that the same ethylene epoxidation catalyst achieves a higher maximum catalyst selectivity than achieved using conventional catalyst conditioning methods.

  Comparative Examples 1-4 illustrate conditioning using an inert gas (e.g., nitrogen, ethylene) at a temperature between 160 <0> C and 245 <0> C without oxygen. As seen in Table 1, these comparative examples resulted in similar selectivities (86.0, 85.7, 85.7, and 85.5%). Comparative Example 5 utilized oxygen in the conditioning feed gas at a temperature of 160 ° C. As can be seen in Table 1, this resulted in similar selectivities as all other comparative examples, including Comparative Example 4, which was also performed at 160 ° C. but using a conditioning gas comprising ethylene. .

  Examples 6 and 7 show the improvement in selectivity as a result of conditioning at 185 ° C. using a conditioning feed gas containing 0.5 and 5% oxygen, respectively. As can be seen in Table 1, the selectivity was improved to 86.8-86.9 compared to all comparative examples, especially compared to comparative example 1, which was the same in the absence of oxygen. And a selectivity of only 86% was achieved.

  Examples 7, 8, and 12 and Comparative Example 5 show the effect of temperature on selectivity using a conditioning feed gas containing oxygen. Comparative Example 5 utilized oxygen in the conditioning feed gas at a temperature of 160 ° C. As shown in Table 1 and FIG. 1B, the selectivity of Comparative Example 5 did not improve, but was similar to Comparative Examples 1-4. Example 7 is a comparative example 5 in which conditioning at a temperature of 185 ° C. using a conditioning supply gas containing oxygen was performed at 160 ° C. for the same time, particularly at the same oxygen concentration, as compared to comparative examples 1 to 5. This shows that the catalyst selectivity is more effective than that of The selectivity in Example 7 was 86.8% relative to Comparative Example 5, which gave only 85.6% selectivity. Further, when the temperature was increased to 220 ° C. as in Example 8, the selectivity was further increased to 88.4%. Further, when the temperature was further increased to 245 ° C. as in Example 12, the selectivity became 88.4%.

  Examples 6, 7, 10, 12 and 14, all performed for 24 hours, show that multiple temperatures (185%, 185%, and 21%) over a range of oxygen concentrations (0.5%, 5%, and 21%), as shown in FIG. 1C. ° C and 245 ° C). All of these examples show an improvement in selectivity compared to Comparative Examples 1-5, and especially to Comparative Examples 1 and 3 conditioned with an inert gas at 185 ° C and 245 ° C, respectively. Was.

  In addition, Examples 11, 12, and 13, all performed at a temperature of 245 ° C and an oxygen concentration of 5%, show an improvement in selectivity over a range of times (6, 24, and 72 hours). All these examples showed improved selectivity compared to Comparative Example 3, as shown in FIG. 1D. For example, very long conditioning times of 100 and 200 hours or more are expected to be effective, but are probably not practical when balanced with the economic impact of not producing ethylene oxide during oxygen conditioning.

Examples 15 to 17
Additional Microreactor Catalyst Testing In the following examples, an ethylene epoxidation catalyst, such as that described in U.S. Pat. used.

  4.41 grams of the ground catalyst sample (14-20 mesh) were loaded into a stainless steel U-shaped microreactor tube. The end of each tube was connected to a gas flow system that allowed gas flow through the catalyst bed in "single flow" operation. The catalyst-containing portion of each tube was immersed in a molten metal bath (heat medium) at 245 ° C.

  In Example 15, a conditioning feed gas containing a balance of 5% by volume oxygen, 2 ppmv ethyl chloride, and nitrogen was fed to the catalyst bed at 245 ° C. for 24 hours with a gas flow of 1760 GHSV. The inlet gas pressure was 1880 kPa (absolute pressure).

  After supplying the conditioning feed gas for 24 hours, the temperature was adjusted to 235 ° C. and the feed gas composition was adjusted to 30 vol% ethylene, 8.4 vol% oxygen, 1.26 vol% carbon dioxide, 3.0 ppmv chloride. The epoxidation feed gas was adjusted to contain a balance of ethyl and nitrogen. The reactor flow was adjusted to 3850 GHSV and the temperature was kept constant for about 24 hours to allow the catalyst to equilibrate, after which the ethylene oxide concentration was 3.61 in the outlet gas stream corresponding to a working speed of 273 kg / m3 / h. The temperature was adjusted to be% by volume. In addition, the ethyl chloride concentration in the feed gas was adjusted to between 1 and 5 ppmv to obtain maximum selectivity at a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream.

  In Example 16, a sweep gas containing 100 mol% nitrogen was supplied to the catalyst bed with a gas flow of 1760 GHSV for 24 hours before introducing the conditioning feed gas. The inlet gas pressure was 1880 kPa (absolute pressure). After supplying the sweep gas for 24 hours, the temperature was adjusted to 245 ° C., and a conditioning feed gas containing a balance of 5% by volume of oxygen and nitrogen was supplied to the catalyst bed at 245 ° C. for 24 hours with a gas flow of 1760 GHSV. The inlet gas pressure was 1880 kPa (absolute pressure).

  After supplying the conditioning feed gas for 24 hours, the temperature was adjusted to 235 ° C. and the feed gas composition was adjusted to a balance of 30% by volume of ethylene, 8.4% by volume of oxygen, 1.26% by volume of carbon dioxide and nitrogen. The epoxidation feed gas was adjusted to contain. The reactor flow was adjusted to 3850 GHSV and the temperature was kept constant for about 24 hours to allow the catalyst to equilibrate, after which the ethylene oxide concentration was 3.61 in the outlet gas stream corresponding to a working speed of 273 kg / m3 / h. The temperature was adjusted to be% by volume. In addition, the ethyl chloride concentration in the epoxidation feed gas was adjusted to between 1 and 5 ppmv to obtain maximum selectivity at a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream.

  In Example 17, a conditioning feed gas containing a balance of 5% oxygen and nitrogen by volume was fed to the catalyst bed at 245 ° C. for 24 hours with a gas flow of 1760 GHSV. The inlet gas pressure was 1880 kPa (absolute pressure). After supplying the conditioning feed gas for 24 hours, the temperature was adjusted to 235 ° C. and the feed gas composition was adjusted to 10% by volume of ethylene, 7% by volume of oxygen, 3% by volume of carbon dioxide, 3.0 ppmv of ethyl chloride, and nitrogen. Was adjusted to an epoxidized feed gas containing a balance of The reactor flow was adjusted to 3850 GHSV and the temperature was held constant for about 12 hours to allow equilibration of the catalyst, after which the temperature was raised to 260 ° C. over 11 hours and then at 260 ° C. for 48 hours. It was kept constant and heat-treated.

  At the end of 48 hours, the temperature was adjusted to 250 ° C. and the epoxidation feed gas was 35% by volume ethylene, 8.4% by volume oxygen, 1.26% by volume carbon dioxide, 3.0 ppmv ethyl chloride, and Adjusted to nitrogen balance. The reactor flow was adjusted to 3850 GHSV and the temperature was adjusted such that the ethylene oxide concentration was 3.61% by volume in the outlet gas stream corresponding to a working speed of 273 kg / m3 / h. In addition, the ethyl chloride concentration in the feed gas was adjusted to between 1 and 5 ppmv to obtain maximum selectivity at a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream.

Examples 15-17 were maintained up to 0.15 kT / m3 CumEO while maintaining a constant ethylene oxide concentration of 3.61% by volume in the outlet gas stream and adjusting the ethyl chloride concentration to achieve maximum selectivity. Carried out. Table 2 provides the performance of Examples 15-17 with respect to the maximum selectivity achieved with cumulative ethylene oxide production between 0.07 and 0.15 kT / m3, which is approximately 11 to 22 days during operation. Equivalent to.

  Example 15 shows that the conditioning method of the present disclosure utilizing a conditioning feed gas comprising oxygen and organic chlorides uses the same ethylene using a conventional catalytic conditioning method such as the method of Comparative Example 3 (85.7%). FIG. 4 shows providing an ethylene epoxidation catalyst that achieves a higher maximum catalyst selectivity (88.0%) than does the epoxidation catalyst.

  Example 16 shows that the conditioning method of the present disclosure, in which the ethylene epoxidation catalyst is contacted with an optional nitrogen sweep gas prior to conditioning, uses a conventional catalyst conditioning method such as the method of Comparative Example 3 (85.7%). FIG. 4 provides an ethylene epoxidation catalyst that achieves a higher maximum catalyst selectivity (88.2%) than does the same ethylene epoxidation catalyst.

  Example 17 shows that the conditioning method of the present disclosure in which the ethylene epoxidation catalyst undergoes an optional heat treatment after conditioning uses the same ethylene epoxidation method using a conventional catalyst conditioning method such as the method of Comparative Example 3 (85.7%). Figure 4 shows that an ethylene epoxidation catalyst is provided that achieves a higher maximum catalyst selectivity (88.5%) than does the epoxidation catalyst.

Examples 18 to 19
Example 18 for comparison, Example 19 according to the invention
Microreactor Catalyst Test In the following examples, an ethylene epoxidation catalyst as described in U.S. Pat. No. 4,766,105 was used that included silver and rhenium promoters deposited on an alpha-alumina support. .

  4.41 grams of the ground catalyst sample (14-20 mesh) were loaded into a stainless steel U-shaped microreactor tube. The end of each tube was connected to a gas flow system that allowed gas flow through the catalyst bed in "single flow" operation. The catalyst-containing portion of each tube was immersed in a molten metal bath (heat medium) at 245 ° C.

  In Comparative Example 18, a conditioning feed gas containing 100 mole% nitrogen was fed to the catalyst bed at 245 ° C. for 24 hours with a gas flow of 1760 GHSV. The inlet gas pressure was 1880 kPa (absolute pressure).

  In Example 19, a conditioning feed gas containing a balance of 5% oxygen and nitrogen by volume was fed to the catalyst bed at 245 ° C. for 24 hours with a gas flow of 1760 GHSV. The inlet gas pressure was 1880 kPa (absolute pressure).

  After feeding the conditioning feed gas for both catalyst beds for 24 hours, the temperature was adjusted to 235 ° C. and the feed gas composition was adjusted to 30% by volume ethylene, 8.4% by volume oxygen, 1.26% by volume carbon dioxide. Adjusted to an epoxidation feed gas containing 3.0 ppmv of ethyl chloride and a nitrogen balance. The reactor flow was adjusted to 3850 GHSV and the temperature was maintained at 235 ° C. for both catalyst beds. The oxygen conversion and selectivity were then monitored for the next 12 hours.

  2A and 2B, which show the oxygen conversion and selectivity of Comparative Example 18 and Example 19 during the first 12 hours after introduction of the epoxidation feed gas. As can be seen in FIG. 2A of Example 19, contacting the catalyst bed with a conditioning feed gas containing 5% oxygen for 24 hours at a temperature of 245 ° C. for about 24 hours results in about 15 Very low oxygen conversions were obtained, starting with an initial oxygen conversion of 8% and gradually increasing to about 35%. This is in contrast to Comparative Example 18, which was not contacted with a conditioning feed gas containing oxygen, resulting in a very high initial oxygen conversion of about 97%, gradually decreasing to 80%. As will be appreciated by those skilled in the art, high oxygen conversion can compromise reactor runaway, catalyst bed hot spots, cracking, and the ability of plant operators to control safety and epoxidation processes. It is undesirable because it can have certain other effects. High oxygen conversion can also cause irreversible damage to the catalyst. Plant operators typically need to take action to avoid high oxygen conversion scenarios by limiting oxygen and / or ethylene feed rates and concentrations, or take extra time to deactivate the catalyst . This leads to very long start times until the same or substantially the same total production rate and final ethylene and / or oxygen concentration as the epoxidation feed gas utilized during normal ethylene oxide production is achieved.

  Further, as can be seen in FIG. 2B, Example 19 achieved a higher selectivity of about 82% 2 hours after introduction of the epoxidation feed gas, as compared to Comparative Example 18, which was 2 hours later. Only about 40% selectivity was achieved and gradually improved to about 48% over the next 10 hours. Increasing selectivity is clearly a significant economic benefit of the present disclosure.

Accordingly, the present disclosure is well-adapted to achieve the objects and advantages mentioned, as well as those inherent therein. The specific embodiments disclosed above are merely exemplary, as the present disclosure may be modified and implemented in different but equivalent ways apparent to those skilled in the art having the benefit of the teachings herein. In addition, no limitations are intended to the structural or design details set forth herein, other than as described in the following claims. It is therefore evident that the particular exemplary embodiments disclosed above may be changed or modified, and all such variations are considered to be within the scope and spirit of the invention. . Although the compositions and methods / processes are described in terms of "comprising,""containing," or "including," the various components or steps are described in the context of the compositions and methods / processes. Also, the various components and steps may be “consistently essential of” or “consistent of”. All numbers and ranges disclosed above may vary somewhat. Whenever a numerical range with a lower and upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, any range of values disclosed herein (from "a to b" or, similarly, in the form of "ab (from a-b)") is used to cover a wider range of values. It should be understood that every number and range subsumed within is described. Also, unless explicitly and clearly defined by the patentee, the terms in the claims have their plain, ordinary meaning. Further, the indefinite article "a" or "an" as used in the claims is defined herein to mean one or more elements it introduces. If there is a conflict between the use of a word or term herein and one or more patents or other documents that may be incorporated herein by reference, the definition consistent with this specification should be adopted. It is.

Claims (10)

A method for conditioning an ethylene epoxidation catalyst, comprising:
Contacting an ethylene epoxidation catalyst comprising a carrier with silver and rhenium co-catalyst deposited thereon with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C. and up to 250 ° C. for at least 2 hours. Contacting the oxidizing catalyst with the conditioning feed gas in an epoxidation reactor in the absence of ethylene.   The method of claim 1, wherein the conditioning gas further comprises an inert gas and an organic chloride.   The method of claim 1, wherein the temperature is at least 185C to a maximum of 250C.   The method of claim 1, wherein the temperature is at least 185 ° C. to a maximum of 245 ° C.   The method of claim 1, wherein the conditioning feed gas comprises oxygen at a concentration of 0.5 to 21 mol%, based on the total conditioning feed gas.   The method of claim 1, wherein the time period is between 2 hours and 200 hours.   The method of claim 1, wherein the time period is between 2 hours and 72 hours.   The method of claim 1, further comprising contacting the ethylene epoxidation catalyst with a sweep gas. The method for epoxidation of ethylene, wherein
Contacting an ethylene epoxidation catalyst comprising a carrier with silver and rhenium co-catalyst deposited thereon with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C. and up to 250 ° C. for at least 2 hours. Contacting the oxidizing catalyst with the conditioning feed gas in an epoxidation reactor in the absence of ethylene; contacting;
Subsequently contacting the ethylene epoxidation catalyst in the epoxidation reactor with an epoxidation feed gas comprising ethylene, oxygen, and an organic chloride. A method for improving the selectivity of an ethylene epoxidation catalyst in an ethylene epoxidation process,
Contacting an ethylene epoxidation catalyst comprising a carrier with silver and rhenium co-catalyst deposited thereon with a conditioning feed gas comprising oxygen at a temperature greater than 180 ° C. and up to 250 ° C. for at least 2 hours. Contacting the oxidizing catalyst with the conditioning feed gas in an epoxidation reactor in the absence of ethylene; contacting;
Subsequently contacting the ethylene epoxidation catalyst in the epoxidation reactor with an epoxidation feed gas comprising ethylene, oxygen, and an organic chloride.

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